package com.example.service.impl;

import cn.hutool.core.bean.BeanUtil;
import com.example.dto.Result;
import com.example.entity.VoucherOrder;
import com.example.mapper.VoucherOrderMapper;
import com.example.service.ISeckillVoucherService;
import com.example.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.example.utils.RedisIdWorker;
import com.example.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.connection.stream.*;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.time.Duration;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Slf4j
@Service
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {

    @Resource
    private ISeckillVoucherService seckillVoucherService;

    @Resource
    private RedisIdWorker redisIdWorker;
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private RedissonClient redissonClient;
    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;
    static {
        SECKILL_SCRIPT= new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }
    //通过开启一个单线程进行异步的处理
    private static final ExecutorService SECKILL_ORDER_EXECUTOR= Executors.newSingleThreadExecutor();

    @PostConstruct
    private void init(){
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }
    private class VoucherOrderHandler implements Runnable {
        String queuename = "stream.orders";

        @Override
        public void run() {
            while (true) {
                try {
                    // 1.获取消息队列中的订单信息 XREADGROUP GROUP g1 c1 COUNT 1 BLOCK 2000 STREAMS s1 >
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1).block(Duration.ofSeconds(2)),
                            StreamOffset.create(queuename, ReadOffset.lastConsumed())
                    );
                    //2.判断消息队列的消息是否获取成功
                    //2.1 判断订单信息是否为空
                    if (list == null || list.isEmpty()) {
                        // 如果为null，说明没有消息，继续下一次循环
                        continue;
                    }
                    // 解析数据
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> value = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(value, new VoucherOrder(), true);
                    //3 如果获取成功，说明有消息，可以下单
                    //3.1.创建订单
                    handleVoucherOrder(voucherOrder);
                    // 4.确认消息 XACK
                    stringRedisTemplate.opsForStream().acknowledge("s1", "g1", record.getId());
                } catch (Exception e) {
                    log.error("处理订单异常", e);
                    //处理异常消息
                    handlePendingList();
                }
            }
        }

        private void handlePendingList() {
            while (true) {
                try {
                    // 1.获取pending-list中的订单信息 XREADGROUP GROUP g1 c1 COUNT 1 BLOCK 2000 STREAMS s1 0
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1),
                            StreamOffset.create("stream.orders", ReadOffset.from("0"))
                    );
                    // 2.判断订单信息是否为空
                    if (list == null || list.isEmpty()) {
                        // 如果为null，说明pendding-list内没有异常消息，结束循环
                        break;
                    }
                    // 解析数据
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> value = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(value, new VoucherOrder(), true);
                    // 3.创建订单
                    handleVoucherOrder(voucherOrder);
                    // 4.确认消息 XACK
                    stringRedisTemplate.opsForStream().acknowledge("s1", "g1", record.getId());
                } catch (Exception e) {
                    log.error("处理pendding订单异常", e);
                    try {
                        Thread.sleep(20);
                    } catch (InterruptedException interruptedException) {
                        interruptedException.printStackTrace();
                    }
                }
            }
        }

//    //通过实现阻塞队列
//    private BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024*1024);
//    private class VoucherOrderHandler implements Runnable{
//        @Override
//        public void run() {
//            while (true){
//                try {
//                    //1.获取队列中的订单信息
//                    VoucherOrder voucherOrder = orderTasks.take();
//                    //2.创建订单
//                    handleVoucherOrder(voucherOrder);
//                } catch (Exception e) {
//                    log.error("处理订单异常",e);
//                }
//            }
//        }
//    }

        private void handleVoucherOrder(VoucherOrder voucherOrder) {
            //1.获取用户
            Long userId = voucherOrder.getUserId();
            // 2.创建锁对象
            RLock redisLock = redissonClient.getLock("lock:order:" + userId);
            // 3.尝试获取锁
            boolean isLock = redisLock.tryLock();
            // 4.判断是否获得锁成功
            if (!isLock) {
                // 获取锁失败，直接返回失败或者重试
                log.error("不允许重复下单！");
                return;
            }
            try {
                //注意：由于是spring的事务是放在threadLocal中，此时的是多线程，事务会失效
                proxy.createVoucherOrder(voucherOrder);
            } finally {
                // 释放锁
                redisLock.unlock();
            }
        }
    }

    private IVoucherOrderService proxy;
    @Override
    public Result seckillVoucher(Long voucherId) {
        //1.1 获取用户id
        Long userId = UserHolder.getUser().getId();
        //1.2 订单id
        long orderId = redisIdWorker.nextId("order");
        //1.3 执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(),
                userId.toString(),
                String.valueOf(orderId)
        );
        //2.判断结果是否为0
        int r= result.intValue();
        if (r != 0){
            //2.1不为0，没有购买资格
            return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
        }
        //3.获取代理对象
        proxy = (IVoucherOrderService)AopContext.currentProxy();
        // 4.返回订单id
        return Result.ok(orderId);
    }


//        //获取用户id
//        Long userId = UserHolder.getUser().getId();
//        //1.执行lua脚本
//        Long result = stringRedisTemplate.execute(
//                SECKILL_SCRIPT,
//                Collections.emptyList(),
//                voucherId.toString(),
//                userId.toString()
//        );
//        //2.判断结果是否为0
//        int r= result.intValue();
//        if (r != 0){
//            //2.1不为0，没有购买资格
//            return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
//        }
//
//        //2.2为0，有购买资格，把下单信息保存到阻塞队列中
//        VoucherOrder voucherOrder = new VoucherOrder();
//        // 2.3.订单id
//        long orderId = redisIdWorker.nextId("order");
//        voucherOrder.setId(orderId);
//        // 2.4.用户id
//        voucherOrder.setUserId(userId);
//        // 2.5.代金券id
//        voucherOrder.setVoucherId(voucherId);
//        //2.6 创建阻塞队列，放入阻塞队列
//        orderTasks.add(voucherOrder);
//        //3.获取代理对象
//        proxy = (IVoucherOrderService)AopContext.currentProxy();
//        // 4.返回订单id
//        return Result.ok(orderId);
//    }



//    @Override
//    public Result seckillVoucher(Long voucherId) {
//        //1.查询优惠卷
//        SeckillVoucher seckillVoucher = seckillVoucherService.getById(voucherId);
//        //2.判断秒杀是否开始
//        if (seckillVoucher.getBeginTime().isAfter(LocalDateTime.now())){
//            return Result.fail("秒杀尚未开始");
//        }
//        //3.判断秒杀是否结束
//        if (seckillVoucher.getEndTime().isBefore(LocalDateTime.now())){
//            return Result.fail("秒杀已经结束");
//        }
//        //4.判断库存是否充足
//        if (seckillVoucher.getStock()< 1 ){
//            return Result.fail("库存不足");
//        }
//        Long userId = UserHolder.getUser().getId();
//        //创建锁对象
////        SimpleRedisLock lock = new SimpleRedisLock(stringRedisTemplate,"order:" + userId);
//        RLock lock = redissonClient.getLock("lock:order:" + userId);
//        //获取锁
//        boolean isLock = lock.tryLock();
//        if (!isLock){
//            return Result.fail("不允许重复下单！");
//        }
//        try {
//            //获取代理对象（事务）
//            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
//            return proxy.createVoucherOrder(voucherId);
//        }finally {
//            //释放锁
//            lock.unlock();
//        }
//    }
    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder) {
        Long userId = voucherOrder.getUserId();
        synchronized(userId.toString().intern()){
            // 5.1.查询订单
            int count = query().eq("user_id", userId).eq("voucher_id", voucherOrder).count();
            // 5.2.判断是否存在
            if (count > 0) {
                // 用户已经购买过了
                log.info("用户已经购买过一次！");
                return;
            }

            // 6.扣减库存
            boolean success = seckillVoucherService.update()
                    .setSql("stock = stock - 1") // set stock = stock - 1
                    .eq("voucher_id", voucherOrder).gt("stock", 0) // where id = ? and stock > 0
                    .update();
            if (!success) {
                // 扣减失败
                log.info("库存不足！");
                return;
            }
            // 7.创建订单
            save(voucherOrder);
        }
    }
}
